Furnace regulating system



Allg- 13, 1940- c. l. GooDHART FURNACE REGULATING SYSTEM 2 sheets-'sheet2 Filed July 17, 1937 Www.

Patented Aug. 13, 1940 UNITED STATES PATENT oFFicE 3 Claims.

This invention relates to a furnace regulating system and moreparticularly to a system in which the draft through the furnace isautomatically controlled. Y y

An object of the invention is to provide means which will automaticallycompensate for the variations in the draft of the ilue passage and whichwill also serve to check the furnace draft quickly when the furnacebecomes sufliciently hot.

Another object is to provide a regulating system in which a blower isused to force the draft through the furnace and in which a iiue draftdoor is automatically operated when the blower ceases to operate. Afurther object is to provide pressure-sensitive means andtemperature-sensitive means for controlling the operation of the blowerand flue draft door.

An embodiment of the invention is illustrated in the accompanyingdrawings in which- Fig l is a view in side elevation, part of the fluepassage being shown in section; Fig. 2, a front elevational view of theblower means; Fig. 3, a detail sectional view of the blower means, theview being taken as illustrated at line 3 of Fig. l; Fig. 4, a detailsectional view taken as indicated at line 4 of Fig. 1, and showing theiiue door control mechanism; and Fig. 5, a schematic view showing the'electrical connections employed.

As illustrated, A designates a furnace; B, blower means for forcing thefurnace draft; C, a flue passage containing a draft door; and D,automatically controlled mechanism controlling the position of the fluedraft door.

The furnace A may be of any type such as warm air, steam, hot water, orother familiar type. The embodiment illustrated is of the steam type andhas a steam pressure control I which is effective for lshutting oi thefurnace draft when the steam pressure in the boiler reaches apredetermined amount.

'I'he flue passage C for carrying away smoke and fumes comprises thecasing II which serves as a common smoke pipe and has its end receivedwithin opening I2 of chimney I3. Casing I'I is here shown as square incross -section, but itv may be of any suitable shape. A cylindricalextension IIa provides the side opening I4 through which air from thefurnace room may enter the flue passage. In this opening a door I5 ofcircular shape to t opening I4 is pivotally supported on a pin I6engaging the sides of extension I Ia. As clearly shown in Fig. 4, pin I6is above the vertical center of the door so that when there is a strongdraft within the flue passage the door will be pulled to open position.For adjusting the door to be pulled open to a lesser or greater extent,I provide a weight I1 adjustably carried on bracket I8. When the weightI8 is moved farther from the pivot I6 a stronger flue draft is (ci.e36-.9)

required to open door I5. Opening I4 and door I5 may be circular orsquare or any other shape that may be desired.

It is well'known that the strength of the ue or chimney draft will varyfrom time to time, due to changes of atmospheric conditions and changesin the direction and velocity of winds, etc. When changes take place tomake the flue draft stronger, door I5 will be opened farther so thatmore air from the furnace room will be admitted into the flue passage,and this will relieve the effective draft through the furnace. In thisway the automatic opening and closing of door I5 serves to maintain apractically constant draft through the furnace.

The operation of door I5 is also controlled by mechanism D whichincludes an arm 20 pivotally mounted at one end to a bracket 2| securedto casing extension I Ia. The other end of arm 20 is equipped with aWeight 22 and is attached by means of chain 23 to the end of finger 24secured to door I5. A solenoid 25 is mounted to bracket 2l above arm 20and is adapted when energized to bring this arm to its raised positionas shown in Fig. 4, and maintain it in this position. A

bar 26 extending within the solenoid may be pivotally connected at itslower end to the central portion of the arm. When the solenoid isenergized, bar 26 is drawn inwardly within the solenoid to raise the arm20. Weight 22 may be moved toward or away from the end of arm 20 toadjust the amount ofy force exerted by this arm. l A stop for limitingthe opening movement of door I5 is provided bythe bolt 2lia which ispivotally attached at its one end to arm 20 and has its other end inslidable engagement with the bracket of solenoid 25. A nut 20h on theupper end of bolt 20B limits the downward movement of the bolt and solimits the downward travel of the arm.

The blower means B includes a casing 30 containing a fan 3| which isdriven by suitable power means such as the electric motor 32. Casing 30has a side extension 33 which provides the intake opening 34. A door 35is pivotally supported in this opening at points above its verticalcenter so that when the fan is in operation the air from the outsidewill press this door open, but when the fan is not in operation thisdoor will effectively close the intake opening. If desired, a solenoid(not shown) may be mounted adjacent door 35 and arranged to open thisdoor almost instantaneously when the electric motor is in operation andpermit the'door to close instantaneously when the motor is deenergized.

The pressure-sensitive and temperature-sensitive control means are moreclearly illustrated in Fig. 5 of the drawings. The steam control I0 isof the diaphragm type having a pivoted arm 4I which is actuated by thediaphragm and which is provided with an adjustable weight 42. When inlower position, the end of arm 4I makes electrical contact with spring43. When the steam pressure becomes greater, arm 4I moves upwardly tobreak this electrical contact. If desired, a mercury tube type switchmay be substituted for the contact arrangement provided by spring 43. Insuch case the mercury switch would be so arranged that the raising ofarm 4I would operate to tilt the mercury tube to break the electricalcontact. The temperature-sensitive control may be any common make ofthermostat in which electrical contact is broken when room temperatureattains a predetermined degree.

The leads 5I and 52 may be connected to any suitable source ofelectrical energy, and each of the controls may be connected asillustrated in Fig. 5. It will be seen that motor 32 and solenoid 25 areconnected in parallel and that each is in series with the thermostat 50and steam control I 0.

The operation of my improved draft regulating system may be brieflystated as follows:

When the temperature of the rooms being heated and the pressure of thesteam in the boiler is below the predetermined amounts for which thedevices 50 and I0 are set, an electrical current will flow from lead 5I,through both of these devices and will energize both solenoid 25 andmotor 32. Operation of motor 32 actuates fan 3| of the blower and causesdoor 35 to open and air to be forced through the furnace, which makesthe furnace re burn briskly. When the room being heated attains thetemperature at which the thermostat 50 is set, this device will operateto break the circuit through both motor and solenoid. The blower thenceases to operate and door 35 closes to shut oi the entrance of anyappreciable amount of air through the draft inlet to the furnace.However, sufficient amounts of air must be allowed to enter the furnaceto take care of combustion and prevent an explosion due to unburnedgases.

During operation of the blower and when the circuit is completed the arm20 is held in raised position by the energized solenoid 25; but whenthis circuit is broken and solenoid 25 is deenergized, this arm is moveddownwardly by weight 22. Downward movement of arm 2U pulls chain 23downwardly and causes door I5 to move quickly into wide open position.So long as this solenoid is deenergized the door will be maintained inthis position.

The opening of door I5 through the action of the solenoid serves toadmit a great amount of air into the flue passage so as to cut down theeffective draft on the furnace to a minimum. The advantage of thisaction is to prevent the hot gases from being drawn up the flue passagewith the strong draft, and causes these gases to be held in the furnaceto give olf their heat to the water or air being heated. Thus door I5 isoperated through two actuating means. During operation of the blowermeans this door is acted upon by the changes in the strength of the fluedraft and when the blower means is not in operation the door is actedupon by the weighted arm 20. It may be noted that the operation of doorI5 through the action of the solenoid is quick and positive while itsnormal operation in overcoming the variation in flue draft is usuallyslow and within narrow limits of movement.

Also when the steam pressure reaches the setting of control II), thecircuit will be broken and both motor and solenoid deenergized with theresults as above explained.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations should be understoodtherefrom but the appended claims should be construed as broadly aspermissible, in View of the prior art.

I claim:

1. In a steam furnace, a blower for forcing air into the draft inlet ofsaid furnace, an electric motor for driving said blower, a flue passagefor conducting smoke away from said furnace, an opening in the side ofsaid flue passage, a door normally closing said opening and effective tomove toward open position when the draft in said passage becomes greaterthan a predetermined amount, mechanism for moving said door to openposition, said mechanism being independent of the draft in said passage,a restraining means for preventing the operation of said mechanism toopen said door and means rendering said restraining means effective onlywhen the steam pressure of said furnace is below a predetermined amountand the temperature of the space being heated by said furnace is below apredetermined degree.

2. In a steam furnace, a draft inlet for introducing air into saidfurnace, a flue passage for conducting smoke away from said furnace, anopening in said flue passage, a door normally closing said opening, saiddoor being movable toward open position when the draft in said passageexceeds a predetermined amount, mechanism for moving said door to openposition, said mechanism being, independent of the draft in saidpassage, restraining means for preventing the operation of saidmechanism to open said door, and means rendering said restraining meansineffective when the steam pressure of said furnace exceeds apredetermined amount or when the temperature of the space being heatedby said furnace exceeds a predetermined degree.

3. In a furnace, a blower for forcing air into the draft inlet of saidfurnace, a flue passage for conducting fumes and smoke away from saidfurnace, a casing mounted on said iiue passage and communicatingtherewith, an opening in said casing, a door pivotally supported in saidcasing normally closing said opening, said door being normally adaptedto move about its pivot toward open position when the draft in said iiuepassage becomes greater than a predetermined amount, and being, in allpositions, outside said flue passage, the amount of movement of saiddoor being dependent upon the strength of the draft in said passage, aweight connected to said door and adapted to move the same to full openposition and to maintain said door in such position, solenoid means forrestraining the action of said Weight when said blower is in operationlthereby permitting said door to move freely from closed position to anyopen position when acted upon by the draft in the flue passage, andsingle means for actuating said blower and said solenoid means, saidsingle means being adapted to be rendered inoperative by a temperaturesensitive control.

' CHARLES I. GOODHART.

